Re: [PATCH v3 2/3] rtc: Add support for the MSTAR MSC313 RTC

[Nobuhiro Iwamatsu <iwamatsu@nigauri.org>]

Hi!

2021年8月20日(金) 2:03 Romain Perier <romain.perier@gmail.com>:
>
> From: Daniel Palmer <daniel@0x0f.com>
>
> This adds support for the RTC block on the Mstar MSC313e SoCs and newer.
>
> Signed-off-by: Daniel Palmer <daniel@0x0f.com>
> Co-developed-by: Romain Perier <romain.perier@gmail.com>
> Signed-off-by: Romain Perier <romain.perier@gmail.com>
> ---
>  MAINTAINERS              |   1 +
>  drivers/rtc/Kconfig      |  10 ++
>  drivers/rtc/Makefile     |   1 +
>  drivers/rtc/rtc-msc313.c | 258 +++++++++++++++++++++++++++++++++++++++
>  4 files changed, 270 insertions(+)
>  create mode 100644 drivers/rtc/rtc-msc313.c
>
> diff --git a/MAINTAINERS b/MAINTAINERS
> index fd25e4ecf0b9..ebacdd5e8878 100644
> --- a/MAINTAINERS
> +++ b/MAINTAINERS
> @@ -2220,6 +2220,7 @@ F:        arch/arm/boot/dts/mstar-*
>  F:     arch/arm/mach-mstar/
>  F:     drivers/clk/mstar/
>  F:     drivers/gpio/gpio-msc313.c
> +F:     drivers/rtc/rtc-msc313.c
>  F:     drivers/watchdog/msc313e_wdt.c
>  F:     include/dt-bindings/clock/mstar-*
>  F:     include/dt-bindings/gpio/msc313-gpio.h
> diff --git a/drivers/rtc/Kconfig b/drivers/rtc/Kconfig
> index 12153d5801ce..9ce4baab5fcf 100644
> --- a/drivers/rtc/Kconfig
> +++ b/drivers/rtc/Kconfig
> @@ -1925,4 +1925,14 @@ config RTC_DRV_WILCO_EC
>           This can also be built as a module. If so, the module will
>           be named "rtc_wilco_ec".
>
> +config RTC_DRV_MSC313
> +       tristate "MStar MSC313 RTC"
> +        depends on ARCH_MSTARV7 || COMPILE_TEST
> +       help
> +         If you say yes here you get support for the Mstar MSC313e On-Chip
> +         Real Time Clock.
> +
> +         This driver can also be built as a module, if so, the module
> +         will be called "rtc-msc313".
> +
>  endif # RTC_CLASS
> diff --git a/drivers/rtc/Makefile b/drivers/rtc/Makefile
> index 2dd0dd956b0e..5efda8a60cee 100644
> --- a/drivers/rtc/Makefile
> +++ b/drivers/rtc/Makefile
> @@ -101,6 +101,7 @@ obj-$(CONFIG_RTC_DRV_MCP795)        += rtc-mcp795.o
>  obj-$(CONFIG_RTC_DRV_MESON)    += rtc-meson.o
>  obj-$(CONFIG_RTC_DRV_MOXART)   += rtc-moxart.o
>  obj-$(CONFIG_RTC_DRV_MPC5121)  += rtc-mpc5121.o
> +obj-$(CONFIG_RTC_DRV_MSC313)   += rtc-msc313.o
>  obj-$(CONFIG_RTC_DRV_MSM6242)  += rtc-msm6242.o
>  obj-$(CONFIG_RTC_DRV_MT2712)   += rtc-mt2712.o
>  obj-$(CONFIG_RTC_DRV_MT6397)   += rtc-mt6397.o
> diff --git a/drivers/rtc/rtc-msc313.c b/drivers/rtc/rtc-msc313.c
> new file mode 100644
> index 000000000000..8cf5d5fb298f
> --- /dev/null
> +++ b/drivers/rtc/rtc-msc313.c
> @@ -0,0 +1,258 @@
> +// SPDX-License-Identifier: GPL-2.0-only
> +/*
> + * Real time clocks driver for MStar/SigmaStar ARMv7 SoCs.
> + * Based on "Real Time Clock driver for msb252x." that was contained
> + * in various MStar kernels.
> + *
> + * (C) 2019 Daniel Palmer
> + * (C) 2021 Romain Perier
> + */
> +
> +#include <linux/clk.h>
> +#include <linux/delay.h>
> +#include <linux/module.h>
> +#include <linux/mod_devicetable.h>
> +#include <linux/platform_device.h>
> +#include <linux/rtc.h>
> +
> +/* Registers */
> +#define REG_RTC_CTRL           0x00
> +#define REG_RTC_FREQ_CW_L      0x04
> +#define REG_RTC_FREQ_CW_H      0x08
> +#define REG_RTC_LOAD_VAL_L     0x0C
> +#define REG_RTC_LOAD_VAL_H     0x10
> +#define REG_RTC_MATCH_VAL_L    0x14
> +#define REG_RTC_MATCH_VAL_H    0x18
> +#define REG_RTC_STATUS_INT     0x1C
> +#define REG_RTC_CNT_VAL_L      0x20
> +#define REG_RTC_CNT_VAL_H      0x24
> +
> +/* Control bits for REG_RTC_CTRL */
> +#define SOFT_RSTZ_BIT          BIT(0)
> +#define CNT_EN_BIT             BIT(1)
> +#define WRAP_EN_BIT            BIT(2)
> +#define LOAD_EN_BIT            BIT(3)
> +#define READ_EN_BIT            BIT(4)
> +#define INT_MASK_BIT           BIT(5)
> +#define INT_FORCE_BIT          BIT(6)
> +#define INT_CLEAR_BIT          BIT(7)
> +
> +/* Control bits for REG_RTC_STATUS_INT */
> +#define RAW_INT_BIT            BIT(0)
> +#define ALM_INT_BIT            BIT(1)
> +
> +struct msc313_rtc {
> +       struct rtc_device *rtc_dev;
> +       void __iomem *rtc_base;
> +       struct clk *clk;

The clk variable is only used in msc313_rtc_probe(). Therefore, it is
not necessary to have it in this structure.

> +};
> +
> +static int msc313_rtc_read_alarm(struct device *dev, struct rtc_wkalrm *alarm)
> +{
> +       struct msc313_rtc *priv = dev_get_drvdata(dev);
> +       unsigned long seconds;
> +
> +       seconds = readw(priv->rtc_base + REG_RTC_MATCH_VAL_L)
> +                       | (readw(priv->rtc_base + REG_RTC_MATCH_VAL_H) << 16);
> +
> +       rtc_time64_to_tm(seconds, &alarm->time);
> +
> +       if (!(readw(priv->rtc_base + REG_RTC_CTRL) & INT_MASK_BIT))
> +               alarm->enabled = 1;
> +
> +       return 0;
> +}
> +
> +static int msc313_rtc_alarm_irq_enable(struct device *dev, unsigned int enabled)
> +{
> +       struct msc313_rtc *priv = dev_get_drvdata(dev);
> +       u16 reg;
> +
> +       reg = readw(priv->rtc_base + REG_RTC_CTRL);
> +       if (enabled)
> +               reg &= ~INT_MASK_BIT;
> +       else
> +               reg |= INT_MASK_BIT;
> +       writew(reg, priv->rtc_base + REG_RTC_CTRL);
> +       return 0;
> +}
> +
> +static int msc313_rtc_set_alarm(struct device *dev, struct rtc_wkalrm *alarm)
> +{
> +       struct msc313_rtc *priv = dev_get_drvdata(dev);
> +       unsigned long seconds;
> +
> +       seconds = rtc_tm_to_time64(&alarm->time);
> +       writew((seconds & 0xFFFF), priv->rtc_base + REG_RTC_MATCH_VAL_L);
> +       writew((seconds >> 16) & 0xFFFF, priv->rtc_base + REG_RTC_MATCH_VAL_H);
> +
> +       msc313_rtc_alarm_irq_enable(dev, alarm->enabled);
> +
> +       return 0;
> +}
> +
> +static bool msc313_rtc_get_enabled(struct msc313_rtc *priv)
> +{
> +       return readw(priv->rtc_base + REG_RTC_CTRL) & CNT_EN_BIT;
> +}
> +
> +static void msc313_rtc_set_enabled(struct msc313_rtc *priv)
> +{
> +       u16 reg;
> +
> +       reg = readw(priv->rtc_base + REG_RTC_CTRL);
> +       reg |= CNT_EN_BIT;
> +       writew(reg, priv->rtc_base + REG_RTC_CTRL);
> +}
> +
> +static int msc313_rtc_read_time(struct device *dev, struct rtc_time *tm)
> +{
> +       struct msc313_rtc *priv = dev_get_drvdata(dev);
> +       u32 seconds;
> +       u16 reg;
> +
> +       if (!msc313_rtc_get_enabled(priv))
> +               return -EINVAL;
> +
> +       reg = readw(priv->rtc_base + REG_RTC_CTRL);
> +       writew(reg | READ_EN_BIT, priv->rtc_base + REG_RTC_CTRL);
> +
> +       /* Wait for HW latch done */
> +       while (readw(priv->rtc_base + REG_RTC_CTRL) & READ_EN_BIT)
> +               udelay(1);
> +
> +       seconds = readw(priv->rtc_base + REG_RTC_CNT_VAL_L)
> +                       | (readw(priv->rtc_base + REG_RTC_CNT_VAL_H) << 16);
> +
> +       rtc_time64_to_tm(seconds, tm);
> +
> +       return 0;
> +}
> +
> +static int msc313_rtc_set_time(struct device *dev, struct rtc_time *tm)
> +{
> +       struct msc313_rtc *priv = dev_get_drvdata(dev);
> +       unsigned long seconds;
> +       u16 reg;
> +
> +       seconds = rtc_tm_to_time64(tm);
> +       writew(seconds & 0xFFFF, priv->rtc_base + REG_RTC_LOAD_VAL_L);
> +       writew((seconds >> 16) & 0xFFFF, priv->rtc_base + REG_RTC_LOAD_VAL_H);
> +
> +       /* Enable load for loading value into internal RTC counter */
> +       reg = readw(priv->rtc_base + REG_RTC_CTRL);
> +       writew(reg | LOAD_EN_BIT, priv->rtc_base + REG_RTC_CTRL);
> +
> +       /* Wait for HW latch done */
> +       while (readw(priv->rtc_base + REG_RTC_CTRL) & LOAD_EN_BIT)
> +               udelay(1);
> +       msc313_rtc_set_enabled(priv);
> +       return 0;
> +}
> +
> +static const struct rtc_class_ops msc313_rtc_ops = {
> +       .read_time = msc313_rtc_read_time,
> +       .set_time = msc313_rtc_set_time,
> +       .read_alarm = msc313_rtc_read_alarm,
> +       .set_alarm = msc313_rtc_set_alarm,
> +       .alarm_irq_enable = msc313_rtc_alarm_irq_enable,
> +};
> +
> +static irqreturn_t msc313_rtc_interrupt(s32 irq, void *dev_id)
> +{
> +       struct msc313_rtc *priv = dev_get_drvdata(dev_id);
> +       u16 reg;
> +
> +       reg = readw(priv->rtc_base + REG_RTC_STATUS_INT);
> +       if (!(reg & ALM_INT_BIT))
> +               return IRQ_NONE;
> +
> +       reg = readw(priv->rtc_base + REG_RTC_CTRL);
> +       reg |= INT_CLEAR_BIT;
> +       reg &= ~INT_FORCE_BIT;
> +       writew(reg, priv->rtc_base + REG_RTC_CTRL);
> +
> +       rtc_update_irq(priv->rtc_dev, 1, RTC_IRQF | RTC_AF);
> +
> +       return IRQ_HANDLED;
> +}
> +
> +static int msc313_rtc_probe(struct platform_device *pdev)
> +{
> +       struct device *dev = &pdev->dev;
> +       struct msc313_rtc *priv;
> +       int ret;
> +       int irq;
> +       unsigned long rate;

Please use reverse christmas tree ordering for local variable.

> +
> +       priv = devm_kzalloc(&pdev->dev, sizeof(struct msc313_rtc), GFP_KERNEL);
> +       if (!priv)
> +               return -ENOMEM;
> +
> +       priv->rtc_base = devm_platform_ioremap_resource(pdev, 0);
> +       if (IS_ERR(priv->rtc_base))
> +               return PTR_ERR(priv->rtc_base);
> +
> +       irq = platform_get_irq(pdev, 0);
> +       if (irq < 0)
> +               return -EINVAL;
> +
> +       priv->rtc_dev = devm_rtc_allocate_device(dev);
> +       if (IS_ERR(priv->rtc_dev))
> +               return PTR_ERR(priv->rtc_dev);
> +
> +       priv->rtc_dev->ops = &msc313_rtc_ops;
> +       priv->rtc_dev->range_max = U32_MAX;
> +
> +       ret = devm_request_irq(dev, irq, msc313_rtc_interrupt, IRQF_SHARED,
> +                              dev_name(&pdev->dev), &pdev->dev);
> +       if (ret) {
> +               dev_err(dev, "Could not request IRQ\n");
> +               return ret;
> +       }
> +
> +       priv->clk = devm_clk_get(dev, NULL);
> +       if (IS_ERR(priv->clk)) {
> +               dev_err(dev, "No input reference clock\n");
> +               return PTR_ERR(priv->clk);
> +       }
> +
> +       ret = clk_prepare_enable(priv->clk);
> +       if (ret) {
> +               dev_err(dev, "Failed to enable the reference clock, %d\n", ret);
> +               return ret;
> +       }
> +
> +       ret = devm_add_action_or_reset(dev, (void (*) (void *))clk_disable_unprepare, priv->clk);
> +       if (ret)
> +               return ret;
> +
> +       rate = clk_get_rate(priv->clk);
> +       writew(rate & 0xFFFF, priv->rtc_base + REG_RTC_FREQ_CW_L);
> +       writew((rate >> 16) & 0xFFFF, priv->rtc_base + REG_RTC_FREQ_CW_H);
> +
> +       platform_set_drvdata(pdev, priv);
> +
> +       return devm_rtc_register_device(priv->rtc_dev);
> +}
> +
> +static const struct of_device_id msc313_rtc_of_match_table[] = {
> +       { .compatible = "mstar,msc313-rtc" },
> +       { }
> +};
> +MODULE_DEVICE_TABLE(of, ms_rtc_of_match_table);

msc313_rtc_of_match_table ?

> +
> +static struct platform_driver msc313_rtc_driver = {
> +       .probe = msc313_rtc_probe,
> +       .driver = {
> +               .name = "msc313-rtc",
> +               .of_match_table = msc313_rtc_of_match_table,
> +       },
> +};
> +
> +module_platform_driver(msc313_rtc_driver);
> +
> +MODULE_AUTHOR("Daniel Palmer <daniel@thingy.jp>");
> +MODULE_AUTHOR("Romain Perier <romain.perier@gmail.com>");
> +MODULE_DESCRIPTION("MStar RTC Driver");
> +MODULE_LICENSE("GPL v2");
> --
> 2.30.2
>

Best regards,
  Nobuhiro

-- 
Nobuhiro Iwamatsu
   iwamatsu at {nigauri.org / debian.org / kernel.org}
   GPG ID: 40AD1FA6